WO2018142445A1

WO2018142445A1 - Control device for synchronous motor

Info

Publication number: WO2018142445A1
Application number: PCT/JP2017/003307
Authority: WO
Inventors: 文雄渡邉; 雅史中村
Original assignee: 東芝三菱電機産業システム株式会社
Priority date: 2017-01-31
Filing date: 2017-01-31
Publication date: 2018-08-09
Also published as: JP6681653B2; JPWO2018142445A1; US10931213B2; US20190356248A1

Abstract

In a drive control unit 7 which carries out vector control of a synchronous motor 3, when the speed of the synchronous motor 3 is at or above a prescribed threshold value, a value obtained by adding a correction angle, at which the D-axis voltage feedback output by a three phase-DQ converter 81 is 0, to a detection angle of a position detection means 4 is used as the reference phase angle of the three phase-DQ converters 81 and 80 and a DQ-three phase converter 78, and when the speed of the synchronous motor 3 is less than the prescribed threshold value, a value obtained by adding a preset low-speed load angle to the detection angle of the position detection means 4 is used as the reference phase angle. During vector control, a power factor 1 is achieved by carrying out control such that a D-axis current is 0.

Description

Control device for synchronous motor

The present invention relates to a control device for a synchronous motor, and more particularly to a control device for a synchronous motor using vector control.

Synchronous motor control devices that drive and control synchronous motors are widely used, but so-called vector control is used, for example, in applications where the load changes greatly. In this case, in order to drive and control the synchronous motor efficiently within a predetermined capacity range of the inverter for driving, it is necessary to make the output current smaller, so the power factor of the synchronous motor is controlled to 1. Is done. For this reason, proposals have been made to calculate the load angle of the synchronous motor by calculating the magnetic flux from the constant of the synchronous motor that changes depending on the load and various currents of the synchronous motor, and to further determine the current reference so that the power factor becomes 1. (For example, refer to Patent Document 1).

Japanese Unexamined Patent Publication No. 2013-31256 (page 4-7, FIG. 1)

According to the technique of Patent Document 1, it is possible to operate the synchronous motor with a power factor of 1. However, since the constant of the synchronous motor needs to be used for the calculation, it is necessary to accurately measure the constant. In addition, the calculation for changing the constant according to the load becomes complicated.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a synchronous motor control device capable of setting the power factor of the synchronous motor to 1 by a relatively simple method.

In order to achieve the above object, a control apparatus for a synchronous motor according to the present invention includes an inverter device that drives electric power supplied from an AC power source to a desired output voltage and frequency, and an output current of the inverter device. Current detecting means for detecting the output voltage, voltage detecting means for detecting the output voltage of the inverter device, position detecting means for detecting the rotation angle of the synchronous motor, and a drive control unit for controlling the output of the inverter device. The drive control unit controls the speed feedback obtained by differentiating the output of the position detection means to be a predetermined speed reference and outputs a Q-axis current reference, and the current detection means The difference between the first three-phase-DQ conversion means for obtaining the Q-axis feedback current and the D-axis feedback current by performing the three-phase-DQ conversion of the detected current, the Q-axis current reference, and the Q-axis feedback current Q-axis current control means for controlling the output to output a Q-axis voltage reference, D-axis current control means for controlling the D-axis feedback current to be 0 and outputting a D-axis voltage reference, DQ-3 phase conversion means for obtaining a voltage reference for each phase of the three-phase output of the inverter device by DQ-3 phase conversion of the Q axis voltage reference and the D axis voltage reference, and PWM control of the voltage reference for each phase PWM control means for outputting a gate signal to the switching elements constituting the inverter device, and second phase to obtain a Q-axis feedback voltage and a D-axis feedback voltage by performing three-phase-DQ conversion on the detection voltage of the voltage detection means Three-phase-DQ conversion means, and voltage control means for outputting a correction angle by PI control so that the D-axis feedback voltage becomes zero, and when the speed of the synchronous motor is equal to or higher than a predetermined threshold value The correction angle is added to the detection angle of the position detection means. The calculated value is used as a reference phase angle of the first three-phase-DQ conversion means, the second three-phase-DQ conversion means, and the DQ-3 phase conversion means, and the speed of the synchronous motor is less than a predetermined threshold value. In this case, a value obtained by adding a preset low-speed load angle to the detection angle of the position detection means is set as the previous phase reference phase angle.

According to the present invention, it is possible to provide a control device for a synchronous motor capable of setting the power factor of the synchronous motor to 1 by a relatively simple method.

The circuit block diagram of the control apparatus of the synchronous motor which concerns on Example 1 of this invention. Explanatory drawing of the control apparatus of the synchronous motor which concerns on Example 1 of this invention. The figure which shows the modification of the control apparatus of the synchronous motor which concerns on Example 1 of this invention. The circuit block diagram of the control apparatus of the synchronous motor which concerns on Example 2 of this invention. The circuit block diagram of the control apparatus of the synchronous motor which concerns on Example 3 of this invention.

Embodiments of the present invention will be described below with reference to the drawings.

Hereinafter, a power conversion device according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 3. 1 is a circuit configuration diagram of a synchronous motor control apparatus according to Embodiment 1 of the present invention.

AC is supplied from the AC power source 1 to the inverter device 2. The inverter device 2 has a converter section (not shown) at its input section, and the converter section converts the input alternating current into a direct current of a desired voltage and supplies it to an inverter section (not shown). The inverter unit converts the direct current into an alternating voltage and drives the synchronous motor 3. The power device constituting the inverter unit of the inverter device 2 is on / off controlled by a gate signal supplied from the drive control unit 7. The synchronous motor 3 is provided with a resolver 4 as position detecting means, and this output is given to the drive controller 7 as a phase angle QO_RES. Further, a current detector 5 and a voltage detector 6 are provided on the output side of the inverter device 2 and are given to the drive control unit 7 as current feedback IU_F, IV_F, IW_F and voltage feedback VU_F, VV_F, VW_F, respectively. The synchronous motor 3 is usually provided with a field winding, and is configured to be supplied with an excitation current from the drive control unit 7, for example.

Next, the internal configuration of the drive control unit 7 will be described.

The phase angle QO_RES obtained by the resolver 4 is converted into speed feedback SP_F by the differentiator 71. The difference between the speed reference SP_R and the speed feedback SP_F given from the outside is calculated by the subtracter 72 and given to the speed controller 73. The speed controller 73 is usually a PI controller. Then, the speed controller 73 adjusts and controls the given difference to be minimum, and outputs the Q-axis current reference IQ_R. The D-axis current reference ID_R is set to 0.

The output of the current detector 5 is given to a three-phase-DQ converter 80 and converted into biaxial current feedback ID_F and IQ_F based on the reference phase angle QO. Here, ID_F and IQ_F are DC amounts, and the reference phase angle QO is corrected by adding a correction angle QO_L, which is an output of an angle correction selector 87 described later, to a phase angle QO_RES detected by the resolver 4 by an adder 88. Phase angle.

The difference between the D-axis current reference ID_R set to 0 and the D-axis current feedback ID_F is calculated by the subtractor 74 and is given to the current controller 76. The difference between the Q-axis current reference IQ_R and the Q-axis current feedback IQ_F is calculated by the subtractor 75 and is given to the current controller 77. The

current controllers

76 and 77 are usually PI controllers. The current controller 76 and the current controller 77 output the D-axis voltage reference ED_R and the Q-axis voltage reference EQ_R, respectively, by adjusting and controlling so that the given difference is minimized. The D-axis voltage reference ED_R and the Q-axis voltage reference EQ_R are supplied to the DQ-3 phase converter 78, and the DQ-3 phase converter 78 outputs three-phase voltage references EU_R, EV_R, EW_R based on the reference phase angle QO. To do. The three-phase voltage references EU_R, EV_R, and EW_R are given to the PWM controller 79. The PWM controller 79 supplies a PWM-modulated gate signal to each power device of the inverter unit so that the output voltage of each phase of the inverter unit of the inverter device 2 becomes the three-phase voltage reference EU_R, EV_R, EW_R. .

The three-phase voltages VU-F, VV-F, and VW-F detected by the voltage detector 6 are given to the three-phase-DQ converter 81, and are converted into two-axis voltage feedbacks ED_F and EQ_F based on the reference phase angle QO. Converted. Here, ED_F and EQ_F are DC amounts, and the reference phase angle QO is a phase angle corrected as described above. The D-axis voltage feedback ED_F and the Q-axis voltage feedback EQ_F are supplied to the absolute value calculator 82, and the D-axis voltage feedback ED_F is divided by the output of the absolute value calculator 82 by the divider 83. That is, the output of the divider 83 is a value normalized so that the D-axis voltage feedback ED_F becomes a constant value regardless of the speed of the synchronous motor 3. The output of the divider 83 is given to the negative input of the subtractor 85 through the filter 84. 0 is given to the positive side input of the subtracter 85, and the voltage controller 86 which is a PI controller adjusts and controls the D-axis voltage feedback ED_F to be 0, and outputs the correction angle QO_L. The correction angle QO_L is given to the adder 88 via the B terminal of the angle correction selector 87. Therefore, when the angle correction selector 87 selects the output of the voltage controller 86, the correction angle QO_L is determined so that the D-axis voltage feedback ED_F which is the output of the three-phase-DQ converter 81 is zero. The phase-locked loop (PLL) operates and QO = QO_RES + QO_L is established. The correction angle QO_L corresponds to a load angle that changes according to the load of the synchronous motor 3 as described later. The angle correction selector 87 is a circuit that selects the signal input output by the switching speed detector 90. The angle correction selector 87 outputs a signal input from the A terminal when the output of the switching speed detector 90 is 0, and outputs a signal input from the B terminal when the output of the switching speed detector 90 is 1. To do. The output of the low-speed load angle setting unit 89 is input to the A terminal of the angle correction selector 87.

By the way, when the operation speed of the synchronous motor 3 becomes low, an error occurs in the detection voltage of the voltage detector 6, and as a result, an error occurs in the correction angle QO_L and the fluctuation becomes large and becomes unstable. For this reason, the speed feedback SP_F is monitored by the switching speed detector 90, and when the speed of the synchronous motor 3 is larger than a predetermined N0, the switching speed detector 90 outputs 1, and the angle correction selector 87 is the voltage as described above. The output of the controller 86 is selected (B terminal is selected for output) to operate the above-described PLL. When the speed becomes less than N0, the switching speed detector 90 outputs 0, and the angle correction selector 87 selects the low speed load angle δ ₀ set by the low speed load angle setter 89 (A terminal). Output selection).

The operation in the above configuration will be described below with reference to the vector diagram shown in FIG. In FIG. 2, the horizontal axis is the sensor D axis, and the vertical axis is the sensor Q axis. The sensor D axis is the magnetic pole direction of the field of the synchronous motor 3. At this time, the induced voltage E0 of the synchronous motor 3 by the field magnetic pole is in the direction of the sensor Q axis as shown in the figure. For example, when the detection phase of the resolver 4 coincides with the sensor Q axis, the detection phase angle QO_RES = 0 ° is defined. When the PLL as described above operates in this state, the reference phase angle QO for DQ conversion is shifted by the correction angle QO_L and is based on the orthogonal coordinates of the D axis (PLL) and the Q axis (PLL) shown in the figure. Conversion is performed. By the operation of the PLL that sets the D-axis voltage feedback ED_F to 0, the output voltage of the inverter device 2 during the PLL becomes only the Q-axis voltage reference EQ_R. Similarly, since the current controller 76 performs control to set the D-axis current reference ID_R to 0, the output current of the inverter device 2 during the PLL is only the Q-axis current reference IQ_R. Therefore, the output voltage and output current of the inverter device 2 are in phase, and a power factor of 1 is achieved. As shown in the figure, the correction angle QO_L indicates the phase difference between the terminal voltage of the synchronous motor 3 and the induced voltage, so the correction angle QO_L corresponds to the load angle of the synchronous motor 3.

Next, FIG. 3 shows input / output characteristics of a switching speed detector 90A, which is a modification of the switching speed detector 90 in the first embodiment. As shown in FIG. 3, the switching speed detector 90A has a so-called hysteresis characteristic. That is, when the speed is less than N0, the switching speed detector 90 outputs 0 and selects the output of the low-speed load angle setting device 89 (output selection of the A terminal), but the speed increases and exceeds N0. However, the output remains 0, and the output is set to 1 only when the speed becomes N1. Similarly, when the speed is N1 or higher, the switching speed detector 90 outputs 1 and selects the output of the voltage controller 86 (output selection of the B terminal). The output remains at 1, and the output is set to 0 only when the speed becomes N0. Thus, if the switching speed detector 90 has a hysteresis characteristic, it is possible to prevent the control from becoming unstable due to unnecessary chattering in the vicinity of the switching speed.

Hereinafter, a control apparatus for a synchronous motor according to Embodiment 2 of the present invention will be described with reference to FIG. FIG. 4 is a circuit configuration diagram of a synchronous motor control apparatus according to Embodiment 2 of the present invention.

The same parts as those in the circuit configuration diagram of the synchronous motor control device according to the first embodiment of the present invention shown in FIG. 1 are denoted by the same reference numerals and the description thereof will be omitted. The difference between the second embodiment and the first embodiment is that a speed decrease switching detector 91 that exchanges information with the switching speed detector 90 and detects the timing immediately before the output of the switching speed detector 90 changes from 1 to 0 is provided. The provided point, the load angle hold circuit 92 for holding the value of the correction angle QO_L, which is the output of the voltage controller 86, is provided by the output signal of the speed decrease switching detector 91, and the load is further loaded by the angle correction selector 87A. The output of the corner hold circuit 92 is also selectable.

The load angle hold circuit 92 holds the input signal by the output signal of the speed decrease switching detector 91 and outputs it. An input terminal C is added to the angle correction selector 87A. The output of the load angle hold circuit 92 is connected to the input terminal C of the angle correction selector 87A. While the output of the switching speed detector 90 is 0 when the synchronous motor 3 is started, the angle correction selector 87A selects the output of the terminal A, the speed of the synchronous motor 3 increases, and the output of the switching speed detector 90 becomes 1. If it is, the angle correction selector 87A selects the output of the terminal B. When the speed of the synchronous motor decreases and the output of the switching speed detector 90 changes from 1 to 0 ′, the angle correction selector 87A selects the output of the terminal C.

With such a configuration, when the operation speed of the synchronous motor 3 is decelerated and becomes the switching speed N0, the correction angle QO_L that is the load angle at that time is first held, and then the speed decrease switching is performed. The detector 91 changes the output of the switching speed detector 90 from 1 to 0 ′. Based on this switching output signal 0 ′, the angle correction selector 87A selects the correction angle QO_LH held by the load angle hold circuit 92 instead of the low speed load angle δ ₀ which is the output of the low speed load angle setter 89. By controlling in this way, the transient disturbance when the low-speed load angle δ ₀ that is the output of the low-speed load angle setting device 89 is not an appropriate value is suppressed, and when the load change is small. It is possible to enter a low speed operation while maintaining a power factor of zero.

Hereinafter, a synchronous motor control apparatus according to Embodiment 3 of the present invention will be described with reference to FIG. FIG. 5 is a circuit configuration diagram of a synchronous motor control apparatus according to Embodiment 3 of the present invention.

The same parts as those in the circuit configuration diagram of the synchronous motor control device according to the first embodiment of the present invention in FIG. 1 are denoted by the same reference numerals in the third embodiment, and the description thereof is omitted. The difference between the third embodiment and the first embodiment is as follows.

That is, the voltage controller 86A, which is a PI controller, is provided with an initial value setting input terminal that enables setting of an initial value of the PI control integration circuit and an enable terminal of the integration circuit, and when a signal from the enable terminal is established, The voltage controller 86A is configured to start PI control using the signal from the initial value setting input terminal as the initial value of the integrating circuit, and the low speed load that is the output of the low speed load angle setting device 89 is applied to the initial value setting input terminal. The angle δ ₀ is connected, and the output of the switching speed detector 90 is given to the enable terminal of the voltage controller 86A.

With such a configuration, the initial value of the output of the voltage controller 86A is equal to the low speed load angle [delta] _0. When the operation speed of the synchronous motor 3 accelerates from the time of startup and reaches the switching speed N0 or N1, the output of the switching speed detector 90 changes from 0 to 1. At this time, the initial value of the output of the voltage controller 86A is equal to the low speed load angle [delta] _0. Therefore, even if the angle correction selector 87 changes the input signal selection from the A terminal that is the output of the low-speed load angle setting device 89 to the B terminal that is the output of the voltage controller 86A, the output of the angle correction selector 87 is still There will be no discontinuous changes.

When the angle correction selector 87 selects the output of the voltage controller 86A, a PLL operation for setting the D-axis voltage feedback ED_F to 0 is started. By adopting the configuration of the third embodiment, it is possible to smoothly switch the load angle by the switching speed detector 90 and the angle correction selector 87 when the speed is increased.

Although the embodiment of the present invention has been described above, this is presented as an example and is not intended to limit the scope of the invention. The novel embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

For example, a speed detector may be used in place of the resolver 4 in FIG. In this case, detection angle information is obtained by integrating speed feedback.

Further, since the filter 84 in FIG. 1 removes harmonics such as a PWM control carrier, it may be inserted into the input side or the output side of the three-phase-DQ converter.

Further, the normal low-speed load angle δ ₀ is set to a predetermined value from the load characteristics of the load driven by the synchronous motor 3, and the correction angle QO_LH held by the load angle hold circuit 92 described in the second embodiment is used. May be. When the load characteristic changes depending on the driving condition, the low speed load angle δ ₀ may be automatically updated to a new correction angle QO_LH every time the operation of the synchronous motor 3 is repeated.

Further, it is obvious that the second embodiment and the third embodiment can be implemented in combination.

DESCRIPTION OF SYMBOLS 1 AC power supply 2 Inverter apparatus 3 Synchronous motor 4 Resolver 5 Current detector 6 Voltage detector 7 Drive control part 71 Differentiator 72 Subtractor 73

Speed controller

74, 75

Subtractor

76, 77 Current controller 78 DQ / 3 phase conversion 79

PWM controller

80, 81 3-phase / DQ converter 82 Absolute value calculator 83 Divider 84 Filter 85

Subtractor

86,

86A Voltage controller

87, 87A Angle correction selector 88 Adder 89 Load angle setting device at

low speed

90, 90A switching speed detector 91 speed drop switching detector 92 load angle hold circuit

Claims

An inverter device for driving a synchronous motor by converting electric power supplied from an AC power source into a desired output voltage and frequency;
Current detecting means for detecting an output current of the inverter device;
Voltage detection means for detecting an output voltage of the inverter device;
Position detecting means for detecting a rotation angle of the synchronous motor;
A drive control unit for controlling the output of the inverter device;
The drive control unit
Speed control means for controlling the speed feedback obtained by differentiating the output of the position detection means to be a predetermined speed reference and outputting a Q-axis current reference;
A first three-phase-DQ conversion unit that obtains a Q-axis feedback current and a D-axis feedback current by performing three-phase-DQ conversion on the detection current of the current detection unit;
Q-axis current control means for controlling the deviation between the Q-axis current reference and the Q-axis feedback current to be 0 and outputting a Q-axis voltage reference;
D-axis current control means for controlling the D-axis feedback current to be 0 and outputting a D-axis voltage reference;
DQ-3 phase conversion means for converting the Q axis voltage reference and the D axis voltage reference into DQ-3 phase to obtain a voltage reference for each phase of the three-phase output of the inverter device;
PWM control means for PWM-controlling the voltage reference of each phase and outputting a gate signal to a switching element constituting the inverter device;
Second three-phase-DQ conversion means for obtaining a Q-axis feedback voltage and a D-axis feedback voltage by performing three-phase-DQ conversion on the detection voltage of the voltage detection means;
Voltage control means for outputting a correction angle by performing PI control so that the D-axis feedback voltage becomes zero,
When the speed of the synchronous motor is equal to or higher than a predetermined threshold, a value obtained by adding the correction angle to the detection angle of the position detection unit is used as the first three-phase-DQ conversion unit and the second three-phase-DQ conversion. And the reference phase angle of the DQ-3 phase conversion means,
When the speed of the synchronous motor is less than a predetermined threshold, a value obtained by adding a preset low-speed load angle to the detection angle of the position detecting means is used as the reference phase angle. .
Giving the predetermined threshold a hysteresis characteristic;
When the speed of the synchronous motor is less than the first set speed, a value obtained by adding the load angle at low speed to the detection angle of the position detecting means is set as the reference phase angle, and the speed of the synchronous motor increases and the first The value obtained by adding the low-speed load angle to the correction angle for the first time when the second set speed is greater than the set speed is set as the reference phase angle, and when the speed of the synchronous motor is equal to or higher than the second set speed A value obtained by adding the correction angle to the detection angle of the position detection unit is set as the reference phase angle, and the detection angle of the position detection unit is set only when the speed of the synchronous motor decreases and becomes less than the first set speed. 2. The synchronous motor control device according to claim 1, wherein a value obtained by adding the low-speed load angle is set as the reference phase angle.
The drive control unit
When the synchronous motor decelerates and its speed falls below the predetermined threshold,
Hold the output of the voltage control means,
The synchronous motor control device according to claim 1 or 2, wherein the held correction angle is used in place of the low-speed load angle.
The drive control unit
When the synchronous motor accelerates and its speed is equal to or higher than the predetermined threshold,
After making the initial value of the integral output of the voltage controller become the load angle at the low speed,
4. The synchronous motor control device according to claim 1, wherein a value obtained by adding the correction angle to a detection angle of the position detection unit is used as the reference phase angle. 5.